cxl: Force psl data-cache flush during device shutdown

cxl: Force psl data-cache flush during device shutdown

BugLink: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1686519
This change adds a force psl data cache flush during device shutdown
callback. This should reduce a possibility of psl holding a dirty
cache line while the CAPP is being reinitialized, which may result in
a UE [load/store] machine check error.

Signed-off-by: Vaibhav Jain <vaibhav@linux.vnet.ibm.com>
Reviewed-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>
Acked-by: Frederic Barrat <fbarrat@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
(cherry picked from commit d7b1946c7925a270062b2e0718aa57b42ba619c0)
Signed-off-by: Breno Leitao <breno.leitao@gmail.com>
Acked-by: Seth Forshee <seth.forshee@canonical.com>
Acked-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>